The present invention relates to surgical tools and methods and, in particular, it concerns a surgical tool and corresponding method for extracting tissue from wall of an organ. The tool and method are particularly suited to procedures for lowering intraocular pressure.
Glaucoma is a disease in which intraocular pressure is a causative risk factor. It affects significant numbers of our population. The treatment of glaucoma is usually medicinal to lower the intraocular pressure. However, medications often fail to control some forms of glaucoma. When further treatment is required, a microsurgical operative procedure is performed.
Conventional surgical techniques for intraocular pressure reduction approach the tissue in the angle of the eye through the conjunctiva. The procedure involves constructing a fistula or opening in the tissue wall, or significant thinning of the tissue in the region of the angle of the eye (sclero-keratectomy or trabeculectomy, to enhance fluid (aqueous humor) flow from the internal portion of the eye through the newly formed opening. This surgery encounters many complications, ranging from loss of the volume and shape of the eye when the fistula is too large through to formation of scar tissue which seals down the fistula. The latter requires peri-operative application or injection of anti-metabolites, harboring a significant risk of bleeding, infections, wound leaks, buttonholing or penetrating vital tissues.
A corneal approach for surgical treatment of glaucoma has been proposed by J. E. Cairns (“Clear-Cornea Trabeculectomy”, Trans Ophthalmol Soc UK 1985;104:142–5) and by R. B. Keillor et al. (“Twenty-Two Cases of Clear Cornea Trabeculectomy”, Australian and New Zealand Journal of Ophthalmology 1986: 14: 339–342). While this approach should theoretically offer advantages of minimizing complications due to damage to the conjunctiva, in practice, the results have been poor, primarily due to complications associated with the typically large corneal incision.
There is therefore a need for tools and methods for reliably removing a block of tissue from the region of the angle of the eye, including at least some trabecular tissue, without the complications resulting from damage to the conjunctiva. It would similarly be useful to provide a tool and method for extracting a tissue block from the wall of a hollow organ.